The present invention relates to an apparatus for avoiding play in the drive of a circular saw. More particularly, the invention is especially suitable for saws for cutting steel and nonferrous metals, wherein high speed steel circular saw blades are used. Generally such circular saws do not comprise so-called braced transmissions, namely, transmissions operating without any play. Therefore, when the cut is started, that is, when only one or two teeth of the circular saw blade engage the workpiece, the disadvantage occurs, that the rotation of the saw blade relative to the workpiece comes temporarily to a standstill. Further rotation of the saw blade occurs only when the drive continues, when all play between the flanks of the gear teeth has been eliminated and when all shafts are subject to a torsion corresponding to the force to be transmitted. The rotation of the saw blade continues to the end of the operation until only one tooth remains in engagement with the workpiece or at the very beginning of a cutting operation, no saw tooth is in engagement with the workpiece. At these points of operation all torsion spring forces in the gear shaft are relaxed and the play between the flanks of the gear teeth is re-established so that the circular saw blade turns faster for a short circumferential length until the next tooth engages the workpiece and the just described sequence begins over again.
It is evident from the just described operation that the saw blade teeth newly engaging the workpiece strike the latter with great force. If, in the course of the further feed advance of the saw three, four, or more teeth simultaneously engage the workpiece, the restoring moment of the circular saw blade resulting from the cutting forces, becomes so large that all gear teeth and bearing plays are eliminated so that all shaft torques are maintained, whereby a uniform sawing takes place without and "hammering action" . When the workpiece is almost cut through the fewer and fewer teeth engage the workpiece, the above described disadvantage occurs again.
The just described "hammering" is not necessarily damaging to the teeth of circular saw blades made of high speed steel or which include so-called inserted teeth of high speed steel. However, if one used in such machines hard metal or carbide tipped saw blades, it is quite possible that fragments of the hard metal teeth split off or that these teeth entirely break out of their soldering or brazing joints, thereby making the entire blade useless.
Because of this problem, circular saw machines that are made for use with carbide tipped blades, are manufactured with braced gear transmissions which are completely free of any blade. There are several approaches to produce such a braced transmission but all are rather involved and hence substantially more expensive than a normal gear transmission.